The invention relates to an accelerator pedal, a pedal assembly, and a motor vehicle.
Accelerator pedals for automobiles with integrated drive devices, so-called “force-feedback pedals”, are known from EP-A-1346 868 and EP-A-1369 763.
EP-A-1346 868 describes a pedal unit in which the pedal element is moveable along an actuation path with respect to a base element. Two return elements are provided to return the pedal element to its initial position. A torque motor is provided on the pedal rotation axis whose stator is attached to the base element, and whose rotor is coupled with the pedal element. The torque motor is connected with a pedal control unit in the form of a microprocessor that includes a control sensor element, e.g., a speed sensor, separation sensor, or temperature sensor. Depending on the measurement value determined by the sensor and a normal condition stored in a buffer, the pedal causes actuation of the torque motor in order to alert the driver of exceeding the normal condition via an increase in the force acting against pedal pressure.
EP-A-1369 763 describes a pedal unit for an automobile that also includes a torque motor as a drive device. A pedal element that may be displaced with respect to a base element includes an accelerator element that causes rotation of a rotational element as the gas pedal is depressed along an actuation path. From the position of the rotational element, the pedal sensor unit creates a corresponding signal for further processing in a throttle unit of the vehicle engine. Spring elements act on the rotating element by means of pedal cables so that the pedal element without actuation pressure will always be returned to its initial position. The torque motor is mounted at a distance from the rotating element, and is connected with it using a motor cable so that the force acting against pedal depression may be adjusted by controlling the engine.
So that emergency operation is possible during a breakdown and potential engine stall, a coupling device is mounted between the engine and the pedal element, e.g., as a ratcheting coupling, pin coupling, motor clutch, multi-disk clutch, or release clutch. The coupling unit consists of two bodies that during normal operation are so held together that they behave as one body. When the engine unit is stopped and blocked, this condition is relieved by strong actuation of the pedal element. For this, depending on implementation, engaged teeth are released, a pin is broken at an intended shear point, or a cable is stretched. Emergency mode is then possible, i.e., the automobile may be driven to a workshop for repair of the unit.
WO-A-03/039899 discloses a number of different embodiments of pedal units with additional return element force. An electromechanical actuator provides additional repositioning force to a pedal element when the actual vehicle speed varies from a nominal speed. The devices are to be so shaped that the actuator itself may not increase vehicle speed under any circumstances. It is further to be ensured that the vehicle driver maintains complete control of the vehicle and actuates the gas pedal correspondingly against the increased force, i.e., he may ‘overpower’ it.
In one embodiment (FIG. 25a, 25b), a pedal element and a pedal housing as base element are provided. The pedal element may pivot with respect to the base element. A rotating disk is so coupled with the pedal element via a lever that it rotates as the pedal element is moved. An electric motor with a rotor and a stator is provided within the pedal housing as a controllable drive device. The force of the stator is transferred to the rotating disk via a transmission device with gear wheels or a toothed belt. The transmission device includes a coupling unit with strike surfaces whereby the engine and rotating disk are coupled when the strike surfaces are engaged with each other.
DE-A-102 38 483 shows a pedal unit element with a pedal element that is so coupled with a rotating element via a lever so that the rotating element rotates when the pedal element is moved. A first return element spring grips the rotating element so that the pedal element is returned by means of a return force. A second return element spring includes a stop that engages with the rotating element after specified depression of the pedal element so that the second return element spring provides additional return element force. A motor drives a setting cylinder via a toothed rod that sets the drive cylinder and thus yields to the depression point after which the additional return element force becomes effective.
In WO-A-03/039899, various embodiments of pedal units are shown in which the force of a motor is used in order to provide additional force on a pedal element. In one embodiment (FIG. 25 a-d), a coupling unit including strike surfaces is positioned in the working path between the motor and the pedal. The motor's rotor drives a first part of the coupling, and a second part of the coupling is coupled via a drive belt to a rotating element that is so linked with the pedal element via a lever that it rotates upon actuation.